This invention relates to a device for diagnosing body cavity interiors with ultrasonic waves wherein the observation can be made in a visual field which is little intercepted and can be well seen.
An ultrasonic wave diagnosing device wherein ultrasonic waves are transmitted and received to diagnose acoustic information within a body cavity has recently come to be used together with an endoscope wherein the inserted part is introduced into the body cavity so as to be able to optically observe the body cavity interior or to cure it by using a forceps. In this ultrasonic wave diagnosing device, when ultrasonic wave pulses are projected onto an object, for example, from the body surface and the projected ultrasonic waves propagate, they will be reflected by a discontinuous boundary surface of an acoustic impedance represented by the product of the density of the medium and the sound velocity, therefore the above mentioned reflected ultrasonic wave pulses will be received and the acoustic information related to the reflection intensity will be utilized for a diagnosis.
When compared with an X-ray device, an ultrasonic wave diagnosing device has many advantages such as information on a living body soft structure can be easily made without using a forming agent, the living body structure will not be destroyed by radioactive rays and the device is easier to handle and is less dangerous. Further, with the recent improvements of the quality and quantity of the information by the progress of the technique on ultrasonic waves, this device is becoming popular as a clinical diagnosing device in the medical field.
As compared to diagnosing wherein ultrasonic wave pulses are transmitted and received on the above mentioned body surface, in the method of diagnosing body cavity interiors with ultrasonic waves wherein ultrasonic wave pulses are transmitted and received at a position near a body organ within a body cavity, high frequency ultrasonic waves (comparatively) with large propagation attenuation can be transmitted and received and therefore there are the advantages that information of a disintegratability and high precision can be obtained and the method will not be influenced by a hypodermic fat layer or the like interposed between objects. Therefore, this method will be used more and more in the future. It is general that this ultrasonic wave diagnosing device to be used as introduced into a body cavity is used integrally with an endoscope as an optically observing means or as fitted with a removable endoscope (optical sighting tube).
Body cavity interior ultrasonic wave diagnosing device of this kind are already suggested in Japanese patent application Nos. 40813 and 40814/1981. In the body cavity interior ultrasonic wave diagnosing device of these prior arts, an incised window is formed on the outer periphery of the right side of an inserted part (as seen from the operator on the hand side in the normal use) in the rear of a curved part and an optical sighting tube is arranged so that an objective optical system at its tip may face the above mentioned incised window from the hand side of the inserted part and a visual field may be rightward from the incised window, because, particularly in the diagnosis of organs within an abdominal cavity, in which the abdominal wall has many blood vessels and the position the organ is determined, therefore the inserting position and inserting direction are medically determined. Therefore, if the visual field is rightward in the normal use, it will be sufficient. However, in the above mentioned prior arts, there have been disadvantages that, in case the elongate inserted part is introduced into a body cavity, the body tissue will contact the outer periphery of the side part from the lower part of the inserted part, the visual field of the optical sighting tube will be obstructed by the tissue and, with only a rightward visual field and curve, a dead angle will be produced for some organ and it will not be able to be diagnosed with ultrasonic waves in some position.